board: dhelectronics: Check pointer before access in dh_get_value_from_eeprom_buffer()

The eip pointer in dh_get_value_from_eeprom_buffer() might be NULL.
The current NULL pointer check happens too late, after the eip was
accessed in variable assignment. Reorder the two, so the NULL pointer
check happens first, and any access second, otherwise the access may
trigger a hang or other undefined behavior.

Signed-off-by: Marek Vasut <marek.vasut@mailbox.org>
Reviewed-by: Christoph Niedermaier <cniedermaier@dh-electronics.com>

diff --git a/board/dhelectronics/common/dh_common.c b/board/dhelectronics/common/dh_common.c
index 8c052c45007a61ec97a9d95e72742b867dc1060d..d3a3f0ff11fb3ea0b69381244f707dd4975046c3 100644 (file)
--- a/board/dhelectronics/common/dh_common.c
+++ b/board/dhelectronics/common/dh_common.c
@@ -131,14 +131,17 @@ int dh_read_eeprom_id_page(u8 *eeprom_buffer, const char *alias)
 int dh_get_value_from_eeprom_buffer(enum eip_request_values request, u8 *data, int data_len,
                                    struct eeprom_id_page *eip)
 {
-       const char fin_chr = (eip->pl.item_prefix & DH_ITEM_PREFIX_FIN_BIT) ?
-                            DH_ITEM_PREFIX_FIN_FLASHED_CHR : DH_ITEM_PREFIX_FIN_HALF_CHR;
-       const u8 soc_coded = eip->pl.item_prefix & 0xf;
+       char fin_chr;
+       u8 soc_coded;
        char soc_chr;
 
        if (!eip)
                return -EINVAL;
 
+       fin_chr = (eip->pl.item_prefix & DH_ITEM_PREFIX_FIN_BIT) ?
+                 DH_ITEM_PREFIX_FIN_FLASHED_CHR : DH_ITEM_PREFIX_FIN_HALF_CHR;
+       soc_coded = eip->pl.item_prefix & 0xf;
+
        /* Copy requested data */
        switch (request) {
        case DH_MAC0: